Costs associated with the treatment of autism and other autism-spectrum disorders (ASDs) are largely unknown, but are likely considerable. Although previous studies of the costs associated with ASDs suffer from a number of limitations, including small sample sizes, limited scope of cost analyses, and data sources that are not current, these studies suggest that costs associated with ASDs could be as high as $1.8 million per year, and that the lifetime costs associated with an individual with autism could be $4.3 million. With prevalence rates currently at 10 cases per 10,000 and increasing overtime, autism is becoming more of a burden on health care and educational systems in the United States. In an effort to better understand the costs associated with ASDs, and characteristics of patients that might affect these costs, the study proposed here will compute cost estimates for traditional health care services (inpatient, outpatient and pharmacy care) for individuals with ASDs. Data on health care service use and costs will come from two general sources: a national health insurance claims database reflecting the health care experiences of over 2.5 million privately insured individuals in the United States, and administrative data from the Medicaid programs of 10 states across the United States. Together, these databases will allow for a comprehensive analysis of health care service use and costs for patients treated in either the public or private sector, and represent a unique opportunity to learn more about the characteristics of patients with ASDs, the kinds of services these patients receive, and the costs of treating this vulnerable population. The aims of this project are: 1) to identify the treated prevalence of ASDs, as well as sociodemographic and clinical characteristics of individuals with ASDs; 2) to identify services used by patients with ASDs and track changes in these services over time and across age groups; and 3) to identify the costs associated with the care of patients with ASDs. The results of the study will be useful for anticipating and responding to the needs of individuals with ASDs, coordinating care across service sectors for patients with ASDs, allocating funds for the research and treatment of these disorders, and designing public and private insurance programs to provide adequate coverage for these patients and reduce the catastrophic financial burden on the families of individuals with ASDs. [unreadable] [unreadable] [unreadable]